Lewis dot structure Calculator - Instant answer

A Lewis structure generator or calculator is an online tool that will help you to find the lewis structure for any atom or molecule. A Lewis structure is also known as the Lewis dot structure is a representation of electrons distribution around the atoms.

Lewis structure helps in determining the lone pair and bond pair in the molecule which is eventually helpful in predicting the shape or geometry of the molecule.

Lewis structure Calculator

How to use the Lewis structure calculator?

In three steps, you can get lewis’s structure for any atom or compound, let’s see how it works.

• Enter the “name” or “chemical formula” of the compound in the given blank box.
• Click the submit button
• After submission, a popup will appear and the lewis structure of the given molecule will be shown.

For example –

Let’s say you have to calculate the Lewis structure for ammonia (NH3).

⇒ Enter either the “Ammonia” or the “NH3” chemical formula in the given empty box of the Lewis structure calculator.

⇒ Click the submit button

⇒ The “Lewis structure generator” will compute the data and the lewis dot structure for ammonia will be shown in the Popup box.

Check related Calculator
Valence electron calculator	Orbital diagram calculator
Electron configuration calculator	Formal charge calculator

As we know, Lewis structure helps in determining the lone pair and bond pair in the molecule which is eventually helpful in predicting the bond angle, shape or geometry of the molecule.

So, check this also –

• Molecular geometry calculator
• Bond angle calculator

How to Calculate Lewis structure?

For most of the compounds, the lewis structure is drawn using 5 or 6 simple steps-

1. Calculate the total number of valence electrons in the molecule
2. Choose the central and outer atoms
3. Draw a skeletal structure
4. Complete the octet of outer atoms first
5. Complete the octet of the central atom (make multiple bonds if necessary)
6. Check the formal charge for atoms

For example – Let’s say we have to calculate the lewis structure for the PCl3 molecule. For that, either you can use the online “Lewis structure calculator” tool or the traditional method.

Let’s follow some steps and draw the lewis structure for PCl3.

Steps for drawing the Lewis dot structure for PCl₃

1. Count total valence electron in PCl₃

First of all, determine the valence electron that is available for drawing the lewis structure of PCl₃ because the lewis diagram is all about the representation of valence electrons around atoms.

So, an easy way to find the valence electron of atoms in the PCl₃ molecule is, just to look at the periodic group of phosphorous and chlorine atoms.

As the phosphorous atom belongs to the 5A group in the periodic table and chlorine is situated in the 7A group, hence, the valence electron for the phosphorous is 5, and for the chlorine atom, it is 7.

⇒ Total number of the valence electron in Phosphorous = 5

⇒ Total number of the valence electrons in chlorine = 7

∴ Total number of valence electron available for the PCl₃ Lewis structure = 5 + 7×3 = 26 valence electrons         [∴ PCl₃ molecule has one phosphorous and three chlorine atoms]

2. Find the least electronegative atom and place it at center

An atom with a less electronegative value is preferable for the central position in the lewis diagram because they are more prone to share the electrons with surrounding atoms.

In the case of the PCl₃ molecule, the phosphorous atom is less electronegative than the chlorine atom.

Hence, put the phosphorous atom at the central position of the lewis diagram and all three chlorine atoms outside to it.

3. Connect outer atoms to the central atom with a single bond

In this step, join all outer atoms to the central atom with the help of a single bond.

In, the PCl₃ molecule, chlorine is the outer atom, and phosphorous is the central atom. Hence, joined them as shown in the figure given below.

Count the number of valence electrons used in the above structure. There are 3 single bonds used in the above structure, and one single bond means 2 electrons.

Hence, in the above structure, (3 × 2) = 6 valence electrons are used from a total of 26 valence electrons available for drawing the PCl₃ Lewis structure.

∴ (26 – 6) = 20 valence electrons

So, we are left with 20 valence electrons more.

4. Place remaining electrons on the outer atom first and complete their octet

Let’s start putting the remaining valence electrons on outer atoms first. In the case of the PCl₃ molecule, chlorine is the outer atom and each of them needs 8 electrons to have a full octet.

Start putting the remaining electrons on chlorine atoms as dots till they complete their octet.

So, all chlorine atoms in the above structure completed their octet, because all of them have 8 electrons(6 electrons represented as dots + 2 electrons in every single bond) in their outer shell.

Now again count the valence electron in the above structure.

In the above structure, there is 18 electrons are represented as dots + three single bonds that contain 6 electrons means a total of 24 valence electrons is used in the above structure.

We have a total of 26 valence electrons available for drawing the lewis structure of PCl₃. And we used 24 valence electrons in the above structure.

∴ (26 – 24) = 2 valence electrons

So, we are left with just 2 valence electrons.

5. Complete the octet of the central atom

Since we have already completed the octet for outer atoms in PCl₃, now, check the octet of the central atom as well.

In PCl₃, the central atom is phosphorous and it requires a total of 8 electrons to have a full valence shell.

If you look at the 4th step structure, the phosphorous atom is attached to three single bonds that means it have 6 electrons, so, it just short of 2 electrons.

We already have the remaining 2 valence electrons, hence, put these two electrons on the phosphorous atom to complete its octet as well.

In the above structure, we see, that each atom completed its octet comfortably, now, Let’s check the formal charge for the above structure to verify whether it’s stable or not.

6. Check the stability with the help of a formal charge concept

The lesser the formal charge on atoms, the better the stability of the lewis diagram.

To calculate the formal charge on an atom. Use the formula given below-

⇒ Formal charge = (valence electrons – nonbonding electrons –   1/2 bonding electrons)

Let’s count the formal charge for the 5th step structure.

 For chlorine atom

⇒ Valence electrons of chlorine = 7

⇒ Nonbonding electrons on chlorine = 6

⇒ Bonding electrons around chlorine (1 single bond) = 2

∴ (7 – 6 – 2/2) = 0 formal charge on the chlorine atoms.

 For phosphorous atom

⇒ Valence electrons of phosphorous = 5

⇒ Nonbonding electrons on phosphorous = 2

⇒ Bonding electrons around phosphorous (3 single bonds) = 6

∴ (5 – 2 – 6/2) = 0 formal charge on the phosphorous central atom.

Hence, in the above PCl₃ lewis structure, all atoms get a formal charge equal to zero.

Therefore, the above lewis dot structure of PCl₃ (Phosphorous trichloride) is most stable and appropriate in nature.

That’s all by working on the methods given above, you can calculate the lewis structure for any compound.

Let’s check our full guide in – How to draw the lewis structure for any compound or ions?

Also, check the Lewis structure for some important molecules –

CO2 Lewis structure	N2H4 Lewis structure	CH4 Lewis structure
NH3 Lewis structure	OF2 Lewis structure	BrF5 Lewis structure
CH2O Lewis structure	CH3COOH Lewis structure	BrO3- Lewis structure
CHCl3 Lewis structure	SO2Cl2 Lewis structure	CN- Lewis structure
BF3 Lewis structure	PCl5 Lewis structure	CH2Cl2 Lewis structure